Generally, microalgae are cultured in flat and shallow ponds constructed outdoors such as culture ponds for chlorella and oxidation ponds for treating waste water. The use of such ponds is, however, accompanied by problems including;
(1) high cost of water agitation, PA1 (2) a large heat loss from the large water surface particularly at night in cold districts, cooling the culture solution of the pond and reducing the rate of reproduction of microalgae in there and PA1 (3) invasion and proliferation of predators such as daphnia and rotifer that cannot be prevented from occurring without using chemicals to a large extent. PA1 (1) a waterway a to be filled with a suspension containing a culture solution and microalgae and adapted to be irradiated with sun beams while being held in contact with ambient air; PA1 (2) an upper hermetically sealed storage tank b for storing said suspension to avoid any contact between the latter and ambient air, said storage tank being provided with a deaeration and a switch valve; PA1 (3) an aeration pipe c arranged and apertured in the storage tank b for feeding pressurized gas into the storage tank b; and PA1 (4) a pressurized gas feeder d
Remarkable developments can be expected in the technological fields of production of edible algae that can reproduce proteins at a rate of more than a hundred times of soy beans, treatment of waste water by means of algae accompanied by utilization of the latter as by products and fixation of carbon dioxide by means of algae as counter-measure for the warming earth. From this point of view, the inventors of the present invention applied for patent for an apparatus for culturing photosynthetic microbes and a method for operating the same also invented by the inventors of the present invention (now filed as Japanese Patent Application Laid-Open No. 4-283146). The present invention relates to this prior art invention.